Machine for printing stamps, in particular on bottle caps

ABSTRACT

Apparatus for feeding the objects to be stamped in front of a device for printing the stamps on the objects. The printing device has a printing surface inking up sub-assembly which is accessible and removable and a printing sub-assembly including a printing surface carrier and enclosed in a completely closed case. An electronic sub-assembly, also completely enclosed, has a counting circuit connected to a device detecting the passage of the objects in front of the printing device, and a safety circuit.

United States Patent [1 1 Pillon Dec. 30, 1975 [54] MACHINE FOR PRINTINGSTAMPS, IN

PARTICULAR ON BOTTLE CAPS [75] Inventor: Marcel Octave Pillon, Gergy,France [73] Assignee: Pont-A-Mousson S.A.,

Pont-A-Mousson, France [22] Filed: Dec. 18, 1973 [21] Appl. No.: 425,891

[30] Foreign Application Priority Data Dec. 22, 1972 France 72.46070[52] US. Cl. ..101/35; lOllDlG. 3; 101/352; 101/425 [51] Int. Cl. B41F17/16; B41F 31/30 [58] Field of Search 101/35, 425, 350, 351, 101/352,DIG. 3

[56] References Cited UNITED STATES PATENTS 2,635,531 4/1953 Bruce eta1. 101/35 2,674,939 4/1954 Brengman 101/35 2,880,669 4/1959 Hirschey101/35 3,094,068 6/1963 Gericke 101/425 3,223,028 12/1965 Brigham 101/403,274,932 9/1966 Caza A. 101/351 3,394,651 7/1968 Ochs 101/35 3,589,2806/1971 Wilde 101/35 3,611,920 10/1971 Timko et a1. 101/35 3,659,5215/1972 Lany 101/35 X Primary Examiner-Clifford D, Crowder Attorney,Agent, or FirmSughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACTApparatus for feeding the objects to be stamped in front of a device forprinting the stamps on the objects. The printing device has a printingsurface inking up sub-assembly which is accessible and removable and aprinting sub-assembly including a printing surface carrier and enclosedin a completely closed case. An electronic sub-assembly, also completelyenclosed, has a counting circuit connected to a device detecting thepassage of the objects in front of the printing device, and a safetycircuit.

15 Claims, 3 Drawing Figures US. Patent Dec.30, 1975 Sheet 1 of23,929,066

'ITTTTT Sheet 2 of 2 3,929,066

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Dec. 30, 1975 US. Patent w\\\\\\\\\\\\\\\\\\\\\\ Wm M N QE MACHINE FORPRINTING STAMPS, IN PARTICULAR ON BOTTLE CAPS The present inventionrelates to a machine for printing stamps on objects and in particularinspection or tax stamps on closing members such as bottle caps.

In such a machine, it must be impossible to print such stamps withoutthe stamps being counted by a counting device included in the machine.It is known, for example from French Pat. No. 1,349,899, to constructmachines of this type in which one or more printing stamps are movedinside a case so as to bring them in contact with the object to beprinted. These machines have the drawback of being discontinuous inoperation.

Moreover, as they are almost entirely mechanical they are particularlycomplex and expensive and do not allow a high printing rate.

An object of the present invention is to overcome these drawbacks.

The invention provides a machine for printing stamps on objects of thetype comprising a device for feedingthe objects and a device forprinting the objects, wherein the printing device comprises asub-assembly for inking up the printing surface and accessible andcapable of being disassembled, a printing sub-assembly comprising aprinting surface carrier and disposed in a chamber of a perfectly closedcase, and an electronic sub-assembly also perfectly enclosed andcomprising a counting circuit connected to a device for detecting thepassage of the objects and a safety circuit.

This machine is therefore simple in construction and cheap and precludesany fraudulent utilization.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic elevational view of a machine according to theinvention for printing a stamp or mark on metal caps for bottles;

FIG. 2 is a partial sectional view to an enlarged scale taken on line 22of FIG. 1, and

FIG. 3 is a diagram of the circuitry of the electronic sub-assembly ofthe machine.

The machine shown in the drawings comprises a fixed table 1 forsupporting bottles B and integral with a fixed vertical frame 2, adevice A for feeding the bottles and a printing device I.

The bottle feeding device A comprises a disc 3 having notches 4 or astar-shaped member which is disposed above the table 1 and parallel tothe latter and is driven in rotation by a motor 5 through the outputshaft 6 or this motor, bevel gears 7 and a shaft 8 to which the disc 3is fixed.

The printing device I is integral with the frame 2 an disposed above aregion in which the disc 3 brings the bottles B to be printed. It isadjustable in height by ing the inking up sub-assembly E and a chamber9" which is substantially closed and rendered inaccessible ortamper-proof by a sealed wall 9 which encloses the printing sub-assemblyD.

The inking up sub-assembly E is detachably mounted in the chamber 9 ofthe case and comprises two parallel support plates 10 which carry an inksupply tank 11 open on a lateral side, a roller 12 for taking up inktangent to the edge of the opening of the tank 11, ink

transfer roller which is displaced by a device (not shown) of the typeconventionally employed in offset printing machines so as to come incontact alternately with the roller 12 and with a roller 14 which istangent to an inkspreading roller 15 and a last roller 16 tangent to theroller 14 and provided for inking up the printing surface.

The roller 14 is rotated by the motor 5 through a belt 17 which extendsaround the shaft 14 of the roller 14. The rollers 13, 15 and 16 arefreely rotative on their shafts 13, 15 and 16 and are driven in rotationat least by the drive roller 14 to which they are tangent. The roller 12is periodically driven in rotation by the roller 14 through a device(not shown) also of the type means of a device (not shown) so as toadapt it to the variable height of the bottles to be printed. Theprinting device is of the offset type and comprises a sub-assembly E forinking up the printing surface, orplate, a sub-assembly D for printingthe printing surface on the caps C and an electronic sub-assembly F fordetecting the caps and counting the printings. l A

The inking up and printing sub-assemblies E and D are disposed in acommon case 9 having two adjacent chambers which are separated by apartition wall, namely a chamber 9 open in its upper part andenclosconventionally employed in offset printing machines.

The detachable sub-assembly E is supported by the shaft 14" of theroller 14 which extends through the walls of the case 9 and it ismaintained in position in the chamber 9 by lugs 18 which are integralwith the upper part of the support plate 10 and bear against heads ofscrews 19 screwed in bosses 20 on the case 9 and on the other hand by across member 21 which connects the lower parts of the two support plates10 and bears against a screw 22 screwed in the case 9.

The printing sub-assembly D is disposed in the chamber 9 of the case andcomprises a printing surface or plate carrying roller 23 which carriesan image of the stamp to be printed and which is tangent to the inkingup roller 16 of the sub-assembly E through an opening 9 which puts thetwo chambers 9 and 9 in communication with each other. This roller 23 isalso tangent to a printing or transfer roller 24 which slightly projectsbeyond the lower face of the case through an opening 9" of the chamber9". Located on each side of the printing roller 24 and perpendicular toits axis are two devices for erasing this roller, each of whichcomprises fixed to one end of a rod 25 an erasing finger portion 26sliding in a guide 27 integral with the case 9 and an electromagnet 28for maintaining the finger member 26 separated from the roller 24 inopposition to the action of a spring 29. The printing surface carryingroller 23 and printing roller 24 are driven by their shafts 23" and 24around which the belt 17 extends. The electronic sub-assembly F is,except for means for measuring the speed of rotation of the motor andtwo detectors detecting the presence of the caps C, placed in a case 30adjacent the case 9 and closed by a sealed cover which therfore preventsaccess to the inside of the case 30. The means for measuring the speedof rotation of the motor is a tachometric dynamo 31 which is screwed onthe shaft of the motor 5. An inductive detector 32 of the presence of ametal cap C of a bottle is placed under the case 9 in the vicinity ofthe opening 9" and printing roller 24. The zone of detection of thisdetector 32 is located upstream of the printing roller 24 with respectto the direction S of feed of the caps C to be printed so as to detectthe caps slightly before their printing. A second inductive detector 33is placed next to the detector 32 in alignment with the axis of theprinting roller 24 so as to detect the caps at the very moment of theirprinting.

Apart from the detectors 32 and 33 and the dynamo 31, the sub-assemblycomprises a pulse generator 34 of the hybrid monostable type (flipflop auni-junction timing circuit) having an input connected to the firstdetector 32 but having moreover a second input connected to thetachometric dynamo 31, this generator producing at a first output 34,when actuated by the detector 32, a signal of duration which is governedby or more precisely inversely proportional to the speed of the dynamo(the voltage of the latter being applied to the terminals of thecapacitor of the RC circuit of the generator). In the absence of asignal at this output 34 there is a signal at its second output 34. Fromany one of its inputs to output 34 and output 34' the generator 34defines signal generator means and signal generating means respectively.This generator 34 is connected, on one hand through its output 34, to anelectronic AND gate or element 35, and, on the other hand through itsoutput 34", to an input of another AND gate or element 36. The otherinput of the gate 35 is connected to the second detector 33 and itsoutput is connected to an electromechanical pulse counter 37. Connectedin parallel with this counter 37 is an electronic device 38 adapted tocheck whether the counter has moved forward one unit in a normalinterval of time for its advance. In the case of imperfect operation ofthe counter 37, this device sets off an alarm 39 and stops the motor 5.

The first detector 32 is also connected to a bistable circuit orflipflop 40 which, under the effect of a pulse from the detector 32,delivers a signal at one, namely 40, of its outputs. There is then nosignal at its second output 40". From any one of its inputs to output 40and output 40", the flipflop 40 defines a signal generator circuit and asignal generating circuit respectively. A reset signal of this flipflopwhich inverts the position of the signal at the output of this flipflopis furnished through an INCLUSIVE OR gate or element 41, eigher by apulse from the electromechanical counter 37 or by a safety key contact42. The output 40 of the flipflop 40 is connected to a second input ofthe AND gate 36 and its output 40" to an input or an electronic ANDgated or element 43 whose second input is connected to the seconddetector 33.

The second detector 33 is also connected between the second input of theAND gate 43, to a third input of the AND gate 36. The outputs of thegates 36 and 43 are connected through electronic INCLUSIVE OR gate orelement 44 to an alarm device 45 which stops the machine. The alarm andmachine stopping devices 39, 45 can only be neutralized by actuation ofthe key safety contact 42 which also once more starts up the machine.

The machine just described operates in the following manner:

In normal operation, the sub-assembly E for inking up the printingsurface is placed in the chamber 9 of the case 9, the positioning screw22 being screwed in such manner that the inking up roller 16 comes incontact with the printing surface carrying roller 23. The bottles B withtheir metal caps C are fed under the printing device I by the notches 4of disc 3 which is driven by the motor 5. The motor also drives therollers 14, 22 and 24. Thus, as it is rotated by the roller 14, theroller 11 takes ink from the tank 12 and transmits this ink to theroller 14 through the transfer roller 13, the spreading roller 15spreading the ink in a continuous film on the roller 14. The lattertransfers its ink to the inking up roller 16 which then inks up theprinting surface carried by the roller 23. The latter then deposits orprints an image of the printing surface on the printing roller 24 whichprints this image when it passes over the cap C through the opening 9"of the case 9.

When the metal cap C passes in front of the first detector 32, thelatter sends a pulse to the generator 34 which then delivers at itsoutput 34 a signal of a length inversely proportional to the speedmeasured by the tachometric dynamo 31. This length of the signal istherefore also inversely proportional to the rate of feed of the bottlesB which are fed by the disc 3 driven by the motor 5. The length of thesignal is such that at the normal rate of feed of the bottles, the metalcap C passes in front of the second detector 33 before the end of thesignal. In this case, the detector 33 delivers a pulse upon the passageof the cap C, that is to say at the moment of the printing of this capby the roller 24, and this pulse is combined in the AND gate 35 withthat of the signal delivered at the output 34 of the generator 34. Thisgate 35 then delivers a pulse which actuates the electromechanicalcounter 37 and causes the latter to count one unit more. Thus, one countcorresponds to-each printing of an image or stamping.

When the machine is started up, the flipflop 40 is in such state thatthere is no signal at its output 40 and a signal at its output 40". Uponthe passage of a cap in front of the detector 32, the latter sends asignal to the flipflop 40 which produces a signal at its output 40 andsuppresses the signal at its output 40". Upon the passage of the cap infront of the detector 33, the latter sends a signal to the AND gate 36which already receives a signal from the output 40" of the flipflop butreceives nothing from the output 34 of the monostable element so thatthis gate 36 does not set off the alarm 45.

When the electromechanical counter 37 has advanced one unit after thepassage of the cap in front of the detector 33, this counter sends apulse through the INCLUSIVE OR gate 41 to the flipflop 40 which resumesits initial state so as to permit the following counting without settingoff the alarm.

Starting up the machine requires, before printing the caps C, that therollers rotate several times in order to achieve the correct inking upof the printing surface on the roller 23 and therefore of the printingroller 24. Consequently, it is essential to be able to operate themachine without bottles and without counting whereas, on the other hand,it is essential that the actual marking of a metal cap C of a bottleresults in a count. The presence of the detectors 32 and 33 satisfiesthese requirements, since there is no counting if the two detectors donot produce pulses, that is to say, when there is no bottle. One theother hand, as soon as bottle caps are detected under normal conditionsof operation, the electromechanical counter 37 is operative.

The electronic sub-assembly F also has for function to prevent any riskof fraud or error and a printing of the caps without counting.

Indeed, if for any reason the electromechanical counter 37 no longeroperates in normal operation of the machine and if the rate of advanceof the counting wheels of the counter decreases, for example owing to asoiling of the wheels, the device 38 for checking that there is a normaladvance of the counter sets off an alarm and stops the machine.

Moreover, if it were attempted to introduce bottles in a directionopposed to the normal direction S, the metal cap C would pass under thesecond detector 33 before passing under the first detector 32 so thatthere would be no coincidence between the pulse of the detector 33 andthe signal which is normally delivered by the output 34 of the generator34 as a consequence of the actuation of the latter by the detector 32.Consequently, no counting could occur, since the AND gate 35 would notbe actuated. Moreover, the pulse of the second detector 33 wouldcoincide with a signal which is given by the output 40" of the flipflop40 hearing in mind that no signal is given by the first detector 32.These signals would give a signal at the output of the AND gate 43 andthis signal would then set off an alarm and cause the complete stoppageof the machine by the action of the OR gate 44. Consequently, themachine could only be started up again by re-inserting the safetycontact key 42 which flips the flipflop 40 and thus suppresses thesignal delivered at the output 40".

Also, if the cap C to be printed passes in front of the first detector32 before passing in front of the second detector but too slowly withrespect to the speed measured by the tachometric dynamo 31, the pulse ofthe detector 33 would not occur during the prolonged signal delivered bythe generator 34 at its output 34 as a consequence of the actuation ofthe latter by the detector 32. In this case, the pulse delivered by thedetector 33 would occur whereas the generator 34 would be at rest, witha signal delivered at the output 34. At this moment, a signal would alsobe delivered at the output 40 of the flipflop 40 owing to the actuationof the latter by the detector 32. These three united signals would thenactuate the AND gate 36 and would set off the alarm and cause stoppageof the machine by the action of the OR gate 44. The starting up of themachine and the suppression of the alarm could then only be achieved byactuating the safety key contact 42.

Finally, in the event of the current being cut off, it is impossible tocause a printing by manual operation, for example by turning by hand theshaft 14 of the roller 14 since in this case the electromagnets 28,which are located in the case and are supplied with current by a normalcurrent supply, are no longer carrying current and the erasing fingermembers 26 are biased by the springs 29 in the guides 27 and bearagainst the pringing roller 24 from which they remove any image of theprinting surface.

Owing to the offset type printing, the stamping of the caps is achievedin a continous manner. The printing device is simple, since it onlycomprises rotating rollers without parts which move in translation or ina reciprocating manner.

When the machine is stopped, the sub-assembly E for inking up theprinting surface to be printed, may be easily cleaned since it issufficent to unscrew the screw 22 and raise the support plates whichcarry therewith the rollers 12, 13, 14, 15 and 16 and the ink supplytank 11.

Another advantage of the invention resides in the simplification of themechanical parts of this machine, due to the utilization of anelectronic system for counting, detecting the caps, actuating themachine and detecting fraudulent use.

An improvement of the invention would consist in employing an ink havinga resin base which would be polymerized immediately under the effect ofa suitable radiation. For drying the ink it would then be sufficient toprovide following on the printing device a source of radiation directedonto the upper part of the caps as they issue from below this device.

Having now described my invention what i claim as new and desire tosecure by letters patent is:

1. A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising rollermeans defining a first surface for receiving ink and roller meansdefining a second surface which is positioned for applying an ink stampon each object through said first opening, a second subassembly whichhas roller means for inking up the first surface and is accessible andremovable from the printing device, said first surface and said rollermeans of the second sub-assembly being in interengagement through saidsecond opening, said first opening and second opening being justsufficient to allow application of the ink stamp on the object andinking of the first surface while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosing theelectronic sub-assembly to render the electronic sub assembly normallyinaccessible, a device for detecting the passage of each object adjacentthe printing sub-assembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producing an electrical signal upon detection of each object,the electronic sub-assembly comprising circuitry including the circuitof the detecting device and a counting circuit connected to the circuitof the detecting device to be responsive to the production of saidsignal, and a safety circuit associated with said circuitry to checkcorrect operation of said circuitry upon passage of each object to saidposition for printing and operative to stop operation of the machine inthe event of incorrect operation of said circuitry.

2. A machine as claimed in claim 1, wherein the counting circuitcomprises a counter having terminals, the safety circuit'comprises acircuit which is for checking that the counting is effected and isconnected to the terminals of the counter and has an output connected tomeans for giving an alarm and stopping operation of the machine.

3. A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising a firstroller, means defining a printing surface carried by the first rollerand a transfer roller which is engaged with the printing surface andpositioned for applying an ink stamp on each object through said firstopening, a sub-assembly which is for inking up the printing surface andis accessible and removable from the printing device, the inking upsubassembly comrising, in the manner of an offset printing machine,inking up rollers for inking up the printing surface, the inking uprollers including a second roller in engagement with said first rollerthrough said second opening, said first opening and second opening beingjust sufficient to allow application of the ink stamp on the object andinking of the first roller while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosing theelectronic sub-assembly to render the electronic sub-assembly ordinarilyinccessible, a device for detecting the passage of each object adjacentthe printing sub-assembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producting an electrical signal upon detection of each object,the electronic sub-assembly comprising circutiry including the circuitof the detecting device and a counting circuit connected to the circuitof the detecting device to be responsive to the production of saidsignal, and a safety circuit associated with said circuitry to checkcorrect operation of said circuitry upon passage of each object to saidposition for printing and operative to stop operation of the machine inthe event of incorrect operations of said circuitry.

4. A machine as claimed in claim 3, wherein the printing sub-assemblycomprises on a side of the transfer roller at least one erasing element,an electromagnet, and spring means biasing the erasing element towardthe transfer roller, the electromagnet being for connection to a powersupply which also supplies power to the machine to be operative inopposition to the action of the spring means to move the erasing elementaway from the transfer roller when power is supplied to the machine.

5. A machine as claimed in claim 3, wherein the case defines a secondchamber to which free access can be had and support means are removablymounted in the second chamber and carry the inking up rollers.

6. A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising rollermeans defining a first surface for receiving ink and roller meansdefining a second surface which is positioned for applying an ink stampon each object through said first opening, a second subassembly whichhas roller means for inking up the first surface and is accessible andremovable from the printing device, said first surface and said rollermeans of the second sub-assembly being in interengagement through saidsecond opening, said first opening and second opening being justsufficient to allow application of the ink stamp on the object andinking of the first surface while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosing theelectronic sub-assembly to render the electronic sub-assembly normallyinaccessible, a device for detecting the passage of each object adjacentthe printing sub-assembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producing an electrical signal upon detection of each object,the electronic sub-assembly comprising circitry including the circuit ofthe detecting device and a counting circuit connected to the circuit ofthe detecting device to be responsive to the production of said signal,and a safety circuit associated with said circuitry to check correctoperation of said circuitry upon passage of each object to said positionfor printing and operative to stop operation of the machine in the eventof incorrect operation of said circuitry, the feeding device imparting apath of travel to the objects and the device for detecting the passageof the objects comprising two detectors disposed one following the otherin said path of travel of the objects, a first detector being upstreamof a region in which the second surface prints the stamp on each objectand the second detector being located in alignment with said region, thefirst detector and the second detector being each capable of producing apulse upon detection of an object, and the counting circuit comprising asignal generator means for generating signals of duration a littlelonger than the time the feed device takes to move an object between thetwo detectors, the signal generator means having an input connected tothe first detector and an output, a counter, and an AND circuit having afirst input connected to said output of the signal generator means, asecond input connected to the second detector and an output connected tothe counter, the safety circuit comprising a signal generating circuithaving an input connected to the first detector and an output, thesignal generating circuit being capable of generating signals at itsoutput when there is no pulse at the input of the signal generatingcircuit, a second AND circuit having a first input connected to theoutput of the signal generator means, a second input connected to thesecond detector and an output, and means for giving an alarm andstopping operation of the machine and connected to the output of thesecond AND circuit, a signal generator circuit having an input and anoutput for generating signals at its output when a pulse arrives at itsinput which input is connected to the first detector, and signalgenerating means having an input connected to the first detector and anoutput and capable of generating signals at its output after a lapse oftime exceeding the time the feeding device takes to feed an objectbetween the two detectors following on the arrival of a pulse at theinput of the fourth circuit, means for giving an alarm and stopping themachine, and a third AND circuit having three inputs respectivelyconnected to the outputs of the signal generator circuit and signalgenerating means and to the second detector and an output connected tothe means for giving an alarm and stopping operation of the machine.

7. A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising rollermeans defining a first surface for receiving ink and roller meansdefining a second surface which is positioned for applying an ink stampon each object through said first opening, a second subassembly whichhas roller means for inking up the first surface and is accessible andremovable from the printing device, and first surface and said rollermeans of the second sub-assembly being in interengagement through saidsecond opening, said first opening and second opening being justsufficient to allow application of the ink stamp on the object andinking of the first surface while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosing theelectronic sub-assembly to render the electronic sub-assembly normallyinaccessible, a device for detecting the passage of each object adjacentthe printing sub-assembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producing an electrical signal upon detection of each object,the electronic sub-assembly comprising circuitry including the circuitof the detecting device and a counting circuit connected to the circuitof the detecting device to be responsive to the production of saidsignal, and a safety circuit associated with said circuitry to checkcorrect operation of said circuitry upon passage of each object to saidposition for printing and operative to stop operation of the machine inthe event of incorrect operation of said circuitry, the feeding deviceimparting a path of travel to the objects and the device for detectingthe passage of the objects comprising two detectors disposed onefollowing the other in said path of travel of the objects, a firstdetector being upstream of a region in which the second surface printsthe stamp on each object and the second detector being located inalignment with said region, and the counting circuit comprising signalgenerator means for generating signals of duration a little longer thanthe time the feed device takes to move an object between the twodectors, the signal generator means having an input connected to thefirst detector and an output, a counter, and an AND circuit having afirst input connected to said output of the signal generator means, asecond input connected to the second detector and an output connected tothe counter.

8. A machine as claimed in claim 7, wherein the signal generator meanshave a second input, the machine comprising a motor for driving thedevice for feeding the objects to the printing device and a tachometricdynamo drivingly connected to the motor and electrically connected tothe second input of the signal generator means to control the durationof the signals.

9. A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining-achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising rollermeans defining a first surface for receiving ink and roller meansdefining a second surface which is positioned for applying an ink stampon each object through said first opening, a second subassembly whichhas roller means for inking up the first surface and is accessible andremovable from the print-' ing device, said first surface and saidroller means of the second sub-assembly being in interengagement throughsaid second opening, said first opening and second opening being justsufficient to allow application of the ink stamp on the object andinking of the first surface while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosing theelectronic sub-assembly to render the electronic sub-assembly normallyinaccessible, a device for detecting the passage of each object adjacentthe printing sub-assembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producing an electrical signal upon detection of each object,the electronic sub-assembly comprising circuitry including the circuitof the detecting device and a counting circuit connected to the circuitof the detecting device to be responsive to the production of saidsignal, and a safety circuit associated with said circuitry to checkcorrect operation of said circuitry upon passage of each object to saidposition for printing and operative to stop operation of the machine inthe event of incorrect operation of said circuitry, the feeding deviceimparting a path of travel to the objects and the device for detectingthe passage of the objects comprising two detectors disposed onefollowing the other in said path of travel of the objects, a firstdetector being upstream of a region in which the second surface printsthe stamp on each object and capable of producing a pulse upon detectionof an object and the second detector being located in alignment withsaid region and capable of producing a pulse upon detection of anobject, the safety circuit comprising a signal generating circuit havingan input connected to the first detector and an output, the signalgenerating circuit being capable of generating signals at its outputwhen there is no pulse at the input of the signal generating circuit,and AND circuit having a first input connected to the output of thesignal generating circuit, a second input connected to the seconddetector and an output, and means for giving an alarm and stoppingoperation of the machine and connected to the output of the AND circuit.

10. A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising rollermeans defining a first surface for receiving ink and roller meansdefining a second surface which is positioned for applying an ink stampon each object through said first opening, a second subassembly whichhas roller means for inking up the first surface and is accessible andremovable from the printing device, said first surface and said rollermeans of the second sub-assembly being in interengagement through saidsecond opening, said first opening and second opening being justsufficient to allow application of the ink stamp on the object andinking of the first surface while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosingtheelectronic sub-assembly to render the electronic sub-assembly normallyinaccessible, a device for detecting the passage of each object adjacentthe printing sub-assembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producting an electrical signal upon detection of each object,the electronic sub-assembly comprising circuitry including the circuitof the detecting device and a counting circuit connected to the circuitof the detecting device to be responsive to the production of saidsignal, and a safety circuit associated with said circuitry to checkcorrect operation of said circuitry upon passage of each object to saidposition for printing and operative to stop operation of the machine inthe event of incorrect operation of said circuitry, the feeding deviceimparting a path of travel to the objects and the device for detectingthe passage of the objects comprising two detectors disposed onefollowing the other in said path of travel of the objects, a firstdetector being upstream of a region in which the second surface printsthe stamp on each object and capable of producing a pulse upon detectionof an object and the second detector being located in alignment withsaid region and capable of producing a pulse upon detection of anobject, the safety circuit comprising a signal generator circuit havingan input and a output for generating signals at its output when a pulsearrives at its input which input is connected to the first detector, andsignal generating means having an input connected to the first detectorand an output and capable of generating signals at its output after alapse of time exceeding the time the feeding device takes to feed anobject between the two detectors following on the arrival of a pulse atthe input of the signal generating means, means for giving an alarm andstopping the machine, and an AND circuit having three inputsrespectively connected to the outputs of the signal generator circuitand signal generating means and to the second detector and an outputconnected to the means for giving an alarm and stopping operation of themachine.

11. A machine as claimed in claim 10, wherein the signal generatorcircuit has a second input and the safety circuit further comprisesre-starting means connected to the second input of the signal generatorcircuit, the signal generator circuit being adapted and arranged to giveno pulse at its output when a pulse arrives at said second input of thesignal generator circuit.

12. A machine as claimed in claim 11, wherein the safety circuitcomprises a signal generating circuit having an input connected to thefirst detector and an output, the signal generating circuit beingcapable of generating signals at its output when there is no pulse atthe input of the signal generating circuit connected to the output ofthe second circuit, a second AND circuit having a first input connectedto the output of the signal generating circuit, a second input connectedto the second detector and an output, and means for giving an alarm andstopping the machine and connected to the output of the second ANDcirucit, the counting circuit having an output, the signal generatingcirucit and the singal generator circuit being constituted by a singleflipflop which has a first input connected to the first detector and asecond input connected to means for re-starting the machine and to theoutput of the conting circuit through an lNSLUSIVE OR circuit, theflipflop having two outputs respectively constituted by 12 said outputof the signal generator circuit and said output of the signal generatingcircuit.

13. A machine as claimed in claim 10, wherein the signal generatorciruit has a second input and the counting circuit has an output whichis connected to the second input of the signal generator circuit whichsignal generator circuit is adapted and arranged to deliver no pulse atits output when a pulse arrives at said second input of the signalgenerator circuit.

14. A machine as claimed in claim 10, wherein the signal generatorcircuit has a second input and the safety circuit further comprisesre-starting means connected to the second input of the signal generatorcircuit, the signal generator circuit being adapted and arranged to giveno pulse at its output when a pulse arrives at said second input of thesignal generator circuit, the machine further comprising an INCLU SlVEOR circuit having two inputs and an output, the re-starting means andthe output of the counting circuit being connected to the two inputs ofthe INCLUSIVE OR circuit whose output is connected to the second inputof the signal generator circuit.

15. A machine as claimed in claim 10, wherein the counting circuitcomprises signal generator means for generating signals of duration alittle longer than the time the feed device takes to move an objectbetween the two detectors, the signal generator means having an inputconnected to the first detector and an output, a counter, and a secondAND circuit having a first input connected to said output of the signalgenerator means, a second input connected to the second detector and anoutput connected to the counter, the signal generator means and thesignal generating means being constituted by a single circuit of themonostable type having an input connected to the first detector and twooutputs which are respectively constituted by said output of the signalgenerator means and said output of the

1. A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising rollermeans defining a first surface for receiving ink and roller meansdefining a second surfaCe which is positioned for applying an ink stampon each object through said first opening, a second sub-assembly whichhas roller means for inking up the first surface and is accessible andremovable from the printing device, said first surface and said rollermeans of the second sub-assembly being in interengagement through saidsecond opening, said first opening and second opening being justsufficient to allow application of the ink stamp on the object andinking of the first surface while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosing theelectronic sub-assembly to render the electronic sub-assembly normallyinaccessible, a device for detecting the passage of each object adjacentthe printing subassembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producing an electrical signal upon detection of each object,the electronic sub-assembly comprising circuitry including the circuitof the detecting device and a counting circuit connected to the circuitof the detecting device to be responsive to the production of saidsignal, and a safety circuit associated with said circuitry to checkcorrect operation of said circuitry upon passage of each object to saidposition for printing and operative to stop operation of the machine inthe event of incorrect operation of said circuitry.
 2. A machine asclaimed in claim 1, wherein the counting circuit comprises a counterhaving terminals, the safety circuit comprises a circuit which is forchecking that the counting is effected and is connected to the terminalsof the counter and has an output connected to means for giving an alarmand stopping operation of the machine.
 3. A machine for printing stampson objects, comprising a device for printing the objects and a devicefor feeding the objects to the printing device, the printing devicecomprising a case defining a chamber which is closed except for a firstopening and a second opening, a printing sub-assembly disposed in thechamber and comprising a first roller, means defining a printing surfacecarried by the first roller and a transfer roller which is engaged withthe printing surface and positioned for applying an ink stamp on eachobject through said first opening, a sub-assembly which is for inking upthe printing surface and is accessible and removable from the printingdevice, the inking up sub-assembly comrising, in the manner of an offsetprinting machine, inking up rollers for inking up the printing surface,the inking up rollers including a second roller in engagement with saidfirst roller through said second opening, said first opening and secondopening being just sufficient to allow application of the ink stamp onthe object and inking of the first roller while rendering access to theinside of said chamber difficult, an electronic sub-assembly, meansenclosing the electronic sub-assembly to render the electronicsub-assembly ordinarily inccessible, a device for detecting the passageof each object adjacent the printing sub-assembly to a position for theprinting of the stamp on the object by the printing sub-assembly, thedetecting device including a circuit producting an electrical signalupon detection of each object, the electronic sub-assembly comprisingcircutiry including the circuit of the detecting device and a countingcircuit connected to the circuit of the detecting device to beresponsive to the production of said signal, and a safety circuitassociated with said circuitry to check correct operation of saidcircuitry upon passage of each object to said position for printing andoperative to stop operation of the machine in the event of incorrectoperations of said circuitry.
 4. A machine as claimed in claim 3,wherein the printing sub-assembly comprises on a side of the transferroller at least one erasing element, an electromagnet, and spring meansbiasing the erasing element toward the transfer roLler, theelectromagnet being for connection to a power supply which also suppliespower to the machine to be operative in opposition to the action of thespring means to move the erasing element away from the transfer rollerwhen power is supplied to the machine.
 5. A machine as claimed in claim3, wherein the case defines a second chamber to which free access can behad and support means are removably mounted in the second chamber andcarry the inking up rollers.
 6. A machine for printing stamps onobjects, comprising a device for printing the objects and a device forfeeding the objects to the printing device, the printing devicecomprising a case defining a chamber which is closed except for a firstopening and a second opening, a printing sub-assembly disposed in thechamber and comprising roller means defining a first surface forreceiving ink and roller means defining a second surface which ispositioned for applying an ink stamp on each object through said firstopening, a second sub-assembly which has roller means for inking up thefirst surface and is accessible and removable from the printing device,said first surface and said roller means of the second sub-assemblybeing in interengagement through said second opening, said first openingand second opening being just sufficient to allow application of the inkstamp on the object and inking of the first surface while renderingaccess to the inside of said chamber difficult, an electronicsub-assembly, means enclosing the electronic sub-assembly to render theelectronic sub-assembly normally inaccessible, a device for detectingthe passage of each object adjacent the printing sub-assembly to aposition for the printing of the stamp on the object by the printingsub-assembly, the detecting device including a circuit producing anelectrical signal upon detection of each object, the electronicsub-assembly comprising circitry including the circuit of the detectingdevice and a counting circuit connected to the circuit of the detectingdevice to be responsive to the production of said signal, and a safetycircuit associated with said circuitry to check correct operation ofsaid circuitry upon passage of each object to said position for printingand operative to stop operation of the machine in the event of incorrectoperation of said circuitry, the feeding device imparting a path oftravel to the objects and the device for detecting the passage of theobjects comprising two detectors disposed one following the other insaid path of travel of the objects, a first detector being upstream of aregion in which the second surface prints the stamp on each object andthe second detector being located in alignment with said region, thefirst detector and the second detector being each capable of producing apulse upon detection of an object, and the counting circuit comprising asignal generator means for generating signals of duration a littlelonger than the time the feed device takes to move an object between thetwo detectors, the signal generator means having an input connected tothe first detector and an output, a counter, and an AND circuit having afirst input connected to said output of the signal generator means, asecond input connected to the second detector and an output connected tothe counter, the safety circuit comprising a signal generating circuithaving an input connected to the first detector and an output, thesignal generating circuit being capable of generating signals at itsoutput when there is no pulse at the input of the signal generatingcircuit, a second AND circuit having a first input connected to theoutput of the signal generator means, a second input connected to thesecond detector and an output, and means for giving an alarm andstopping operation of the machine and connected to the output of thesecond AND circuit, a signal generator circuit having an input and anoutput for generating signals at its output when a pulse arrives at itsinput which input is connected to the firsT detector, and signalgenerating means having an input connected to the first detector and anoutput and capable of generating signals at its output after a lapse oftime exceeding the time the feeding device takes to feed an objectbetween the two detectors following on the arrival of a pulse at theinput of the fourth circuit, means for giving an alarm and stopping themachine, and a third AND circuit having three inputs respectivelyconnected to the outputs of the signal generator circuit and signalgenerating means and to the second detector and an output connected tothe means for giving an alarm and stopping operation of the machine. 7.A machine for printing stamps on objects, comprising a device forprinting the objects and a device for feeding the objects to theprinting device, the printing device comprising a case defining achamber which is closed except for a first opening and a second opening,a printing sub-assembly disposed in the chamber and comprising rollermeans defining a first surface for receiving ink and roller meansdefining a second surface which is positioned for applying an ink stampon each object through said first opening, a second sub-assembly whichhas roller means for inking up the first surface and is accessible andremovable from the printing device, and first surface and said rollermeans of the second sub-assembly being in interengagement through saidsecond opening, said first opening and second opening being justsufficient to allow application of the ink stamp on the object andinking of the first surface while rendering access to the inside of saidchamber difficult, an electronic sub-assembly, means enclosing theelectronic sub-assembly to render the electronic sub-assembly normallyinaccessible, a device for detecting the passage of each object adjacentthe printing sub-assembly to a position for the printing of the stamp onthe object by the printing sub-assembly, the detecting device includinga circuit producing an electrical signal upon detection of each object,the electronic sub-assembly comprising circuitry including the circuitof the detecting device and a counting circuit connected to the circuitof the detecting device to be responsive to the production of saidsignal, and a safety circuit associated with said circuitry to checkcorrect operation of said circuitry upon passage of each object to saidposition for printing and operative to stop operation of the machine inthe event of incorrect operation of said circuitry, the feeding deviceimparting a path of travel to the objects and the device for detectingthe passage of the objects comprising two detectors disposed onefollowing the other in said path of travel of the objects, a firstdetector being upstream of a region in which the second surface printsthe stamp on each object and the second detector being located inalignment with said region, and the counting circuit comprising signalgenerator means for generating signals of duration a little longer thanthe time the feed device takes to move an object between the twodectors, the signal generator means having an input connected to thefirst detector and an output, a counter, and an AND circuit having afirst input connected to said output of the signal generator means, asecond input connected to the second detector and an output connected tothe counter.
 8. A machine as claimed in claim 7, wherein the signalgenerator means have a second input, the machine comprising a motor fordriving the device for feeding the objects to the printing device and atachometric dynamo drivingly connected to the motor and electricallyconnected to the second input of the signal generator means to controlthe duration of the signals.
 9. A machine for printing stamps onobjects, comprising a device for printing the objects and a device forfeeding the objects to the printing device, the printing devicecomprising a case defining a chamber which is closed except for a firstopening and a second opening, a printing suB-assembly disposed in thechamber and comprising roller means defining a first surface forreceiving ink and roller means defining a second surface which ispositioned for applying an ink stamp on each object through said firstopening, a second sub-assembly which has roller means for inking up thefirst surface and is accessible and removable from the printing device,said first surface and said roller means of the second sub-assemblybeing in interengagement through said second opening, said first openingand second opening being just sufficient to allow application of the inkstamp on the object and inking of the first surface while renderingaccess to the inside of said chamber difficult, an electronicsub-assembly, means enclosing the electronic sub-assembly to render theelectronic sub-assembly normally inaccessible, a device for detectingthe passage of each object adjacent the printing sub-assembly to aposition for the printing of the stamp on the object by the printingsub-assembly, the detecting device including a circuit producing anelectrical signal upon detection of each object, the electronicsub-assembly comprising circuitry including the circuit of the detectingdevice and a counting circuit connected to the circuit of the detectingdevice to be responsive to the production of said signal, and a safetycircuit associated with said circuitry to check correct operation ofsaid circuitry upon passage of each object to said position for printingand operative to stop operation of the machine in the event of incorrectoperation of said circuitry, the feeding device imparting a path oftravel to the objects and the device for detecting the passage of theobjects comprising two detectors disposed one following the other insaid path of travel of the objects, a first detector being upstream of aregion in which the second surface prints the stamp on each object andcapable of producing a pulse upon detection of an object and the seconddetector being located in alignment with said region and capable ofproducing a pulse upon detection of an object, the safety circuitcomprising a signal generating circuit having an input connected to thefirst detector and an output, the signal generating circuit beingcapable of generating signals at its output when there is no pulse atthe input of the signal generating circuit, and AND circuit having afirst input connected to the output of the signal generating circuit, asecond input connected to the second detector and an output, and meansfor giving an alarm and stopping operation of the machine and connectedto the output of the AND circuit.
 10. A machine for printing stamps onobjects, comprising a device for printing the objects and a device forfeeding the objects to the printing device, the printing devicecomprising a case defining a chamber which is closed except for a firstopening and a second opening, a printing sub-assembly disposed in thechamber and comprising roller means defining a first surface forreceiving ink and roller means defining a second surface which ispositioned for applying an ink stamp on each object through said firstopening, a second sub-assembly which has roller means for inking up thefirst surface and is accessible and removable from the printing device,said first surface and said roller means of the second sub-assemblybeing in interengagement through said second opening, said first openingand second opening being just sufficient to allow application of the inkstamp on the object and inking of the first surface while renderingaccess to the inside of said chamber difficult, an electronicsub-assembly, means enclosing the electronic sub-assembly to render theelectronic sub-assembly normally inaccessible, a device for detectingthe passage of each object adjacent the printing sub-assembly to aposition for the printing of the stamp on the object by the printingsub-assembly, the detecting device including a circuit producting anelectrical signal upon detection of each object, tHe electronicsub-assembly comprising circuitry including the circuit of the detectingdevice and a counting circuit connected to the circuit of the detectingdevice to be responsive to the production of said signal, and a safetycircuit associated with said circuitry to check correct operation ofsaid circuitry upon passage of each object to said position for printingand operative to stop operation of the machine in the event of incorrectoperation of said circuitry, the feeding device imparting a path oftravel to the objects and the device for detecting the passage of theobjects comprising two detectors disposed one following the other insaid path of travel of the objects, a first detector being upstream of aregion in which the second surface prints the stamp on each object andcapable of producing a pulse upon detection of an object and the seconddetector being located in alignment with said region and capable ofproducing a pulse upon detection of an object, the safety circuitcomprising a signal generator circuit having an input and a output forgenerating signals at its output when a pulse arrives at its input whichinput is connected to the first detector, and signal generating meanshaving an input connected to the first detector and an output andcapable of generating signals at its output after a lapse of timeexceeding the time the feeding device takes to feed an object betweenthe two detectors following on the arrival of a pulse at the input ofthe signal generating means, means for giving an alarm and stopping themachine, and an AND circuit having three inputs respectively connectedto the outputs of the signal generator circuit and signal generatingmeans and to the second detector and an output connected to the meansfor giving an alarm and stopping operation of the machine.
 11. A machineas claimed in claim 10, wherein the signal generator circuit has asecond input and the safety circuit further comprises re-starting meansconnected to the second input of the signal generator circuit, thesignal generator circuit being adapted and arranged to give no pulse atits output when a pulse arrives at said second input of the signalgenerator circuit.
 12. A machine as claimed in claim 11, wherein thesafety circuit comprises a signal generating circuit having an inputconnected to the first detector and an output, the signal generatingcircuit being capable of generating signals at its output when there isno pulse at the input of the signal generating circuit connected to theoutput of the second circuit, a second AND circuit having a first inputconnected to the output of the signal generating circuit, a second inputconnected to the second detector and an output, and means for giving analarm and stopping the machine and connected to the output of the secondAND cirucit, the counting circuit having an output, the signalgenerating cirucit and the singal generator circuit being constituted bya single flipflop which has a first input connected to the firstdetector and a second input connected to means for re-starting themachine and to the output of the conting circuit through an INSLUSIVE ORcircuit, the flipflop having two outputs respectively constituted bysaid output of the signal generator circuit and said output of thesignal generating circuit.
 13. A machine as claimed in claim 10, whereinthe signal generator ciruit has a second input and the counting circuithas an output which is connected to the second input of the signalgenerator circuit which signal generator circuit is adapted and arrangedto deliver no pulse at its output when a pulse arrives at said secondinput of the signal generator circuit.
 14. A machine as claimed in claim10, wherein the signal generator circuit has a second input and thesafety circuit further comprises re-starting means connected to thesecond input of the signal generator circuit, the signal generatorcircuit being adapted and arranged to give no pulse at its output when apulse arrives at saId second input of the signal generator circuit, themachine further comprising an INCLUSIVE OR circuit having two inputs andan output, the re-starting means and the output of the counting circuitbeing connected to the two inputs of the INCLUSIVE OR circuit whoseoutput is connected to the second input of the signal generator circuit.15. A machine as claimed in claim 10, wherein the counting circuitcomprises signal generator means for generating signals of duration alittle longer than the time the feed device takes to move an objectbetween the two detectors, the signal generator means having an inputconnected to the first detector and an output, a counter, and a secondAND circuit having a first input connected to said output of the signalgenerator means, a second input connected to the second detector and anoutput connected to the counter, the signal generator means and thesignal generating means being constituted by a single circuit of themonostable type having an input connected to the first detector and twooutputs which are respectively constituted by said output of the signalgenerator means and said output of the signal generating means.